The present invention relates generally to winches and more particularly to winches which comprise a rotatable ratchet wheel that can be locked in place using a pivotable pawl.
In the retail industry, it is well known for a length of light to medium gauge wire to be secured at each of its ends to a fixed object, such as a pole, post or wall. With the length of wire held taut between the pair of fixed objects, articles for sale are often hung upon the wire at a considerable height above floor level in order to maximize their visibility. Examples of retail environments in which a length of wire is used to display products for sale include art galleries, trade shows, conventions, and warehouse or wholesale style stores.
It has been found that there is a need for a mechanical device which can be used to perform both of the following functions: (1) to support one end of the length of wire and (2) to provide mechanical means for both tightening the length of wire (in order to more adequately support heavy objects) and loosening the length of wire (in order to lower supported objects to a height which can then be accessed by an employee at floor level).
Accordingly, a winch is a mechanical device which is commonly used in the art to both support one end of a length or wire and mechanically adjust the tautness of said length of wire.
A winch typically includes a rotatable cylindrical drum (also commonly referred to as a spool or spindle) to which one end of the wire is secured, the drum being rotatably mounted on a rigid support frame. A manually operable crank is fixedly coupled to one end of the drum such that, through rotation of the crank, the wire can be wound, or coiled, around the drum, thereby tightening the length of wire. In order to prevent the wire from unwinding from the drum, the winch is typically provided with a ratchet and pawl locking mechanism.
Specifically, a ratchet (also commonly referred to herein as a ratchet wheel) is fixedly mounted on the drum, the ratchet comprising a plurality of outwardly-extending ratchet teeth. In addition, a pawl is pivotally mounted on the support frame for the winch and is typically spring-biased to sequentially engage the teeth of the ratchet to prevent the drum from rotating such that the wire unwinds therefrom, as will be described further in detail below.
In use, a winch of the type described above can be used in the following manner to support one end of a length or wire and to mechanically adjust the tautness of said length of wire. First, the first end of the length of wire is fixedly mounted on a secure object, such as a pole or beam. Then, the second end of the length of wire is connected to the drum of the winch (e.g., by tying the end of the wire to the drum). In turn, the winch is preferably mounted on a support structure, such as a beam, pole or wall.
Supported at both ends onto fixed objects, the length of wire can be tightened in the following manner using the winch. Specifically, using the manually operable crank, the drum is rotated in a first direction which, in turn, causes the second end of the wire to wind around the drum, thereby tightening the length of wire. It should be noted that due to the ratchet-shaped configuration of the teeth on the ratchet wheel, the spring-biased pawl rides along the outer periphery of the ratchet wheel and sequentially deflects away from the tips of the ratchet teeth without impeding rotation of the drum.
Upon withdrawal of the rotational force applied to the drum, the tension within the wire will naturally cause the second end of the wire to unwind from the drum (i.e., cause the drum to rotate in the opposite direction). However, it is to be understood that, upon the initial rotation of the drum in the second direction, the pawl is biased by a spring to engage a tooth on the ratchet wheel so as to impede further rotation. In this manner, the spring-biased pawl serves as a locking device for maintaining the wire taut.
In the situation where the user wishes to loosen the wire (i.e., rotate the drum in the second direction such that the wire can unwind therefrom), the user can apply a rotational force to the pawl (i.e., greater than the internal force of the spring) that causes the pawl to disengage from the ratchet wheel. With the pawl manually disengaged from the ratchet wheel, the tension within the wire will cause the wire to unwind from the drum (i.e., loosen).
Although well known in the art, winches of the type as described above which include a pawl biased by a spring suffer from a couple notable drawbacks.
As a first drawback, winches of the type as described above which utilize a spring for disposing a pawl into selective engagement with a ratchet wheel have been found to be highly unreliable in nature. In particular, over time, the strength of the spring may weaken to the point that the overall functionality of the winch is significantly compromised, which is highly undesirable.
As a second drawback, winches of the type as described above which utilize a spring for disposing a pawl into selective engagement with a ratchet wheel are highly complex mechanical devices (i.e., they include a number of moving mechanical components), thereby rendering said winches relatively costly to manufacture, which is highly undesirable.